The present disclosure relates to crystalline Form 1, Form 2, Form 3 of Ponesimod, a selective S1P1 receptor modulator, and preparation methods thereof. The X-ray powder diffraction pattern of Form 1 shows characteristic peaks at 2theta values of 18.1°±0.2°, 14.6°±0.2°, 11.3°±0.2°； the X-ray powder diffraction pattern of Form 2 shows characteristic peaks at 2theta values of 3.8°±0.2°, 10.8°±0.2°, 6.1°±0.2°； the X-ray powder diffraction pattern of Form 3 shows characteristic peaks at 2theta values of 12.2°±0.2°, 6.2°±0.2°, 5.6°±0.2°. The crystalline forms in present disclosure not only have better stability but also have higher solubility compared with the prior art forms, they are more suitable for the formulation development of Ponesimod.
